Furthering Understanding of the Role of Cereal Rye Allelochemicals in the Cereal Rye-Corn Production System

Date: 
Aug 2019

Issue

Despite the environmental benefits associated with a cereal rye cover crop there may be unintended negative consequences, for example, yield reductions in the following corn crop. Potential causes of this yield decline include seedling disease and allelopathy. Cereal rye serves as a green bridge for soil-borne pathogens of corn, and lower yields that can occur in corn planted after a cereal rye cover crop have been attributed to greater seedling disease. Allelopathy is a complex process in which plants release chemical compounds that affect the growth and physiological processes of other plants. Allelochemicals also affect plant-microbiome interactions.

Objective

This goal of this project is to better understand interactions between corn growth, allelochemicals secreted by cereal rye used as a cover crop and seedling disease pathogens. This information will be used to refine recommended best management practices for rye-corn production systems in Iowa.

Approach

The project will evaluate the growth of corn and Pythium spp. and development of seedling disease in the presence of leachates from two varieties of rye that produce either high or low amounts of allelochemicals.

Project Updates

June 2020

FINAL REPORT:

In general, MBOA reduced corn coleoptile length and radicle length and did not cause root rot across all temperatures tested (13°C, 16°C, or room temperature/20-22°C). In general, all Pythium spp. that were tested were tolerant to MBOA at 0.0625 and 0.125 mg/ml across all temperatures. Greater root rot severity in corn was observed on corn seedlings grown in the presence of Pythium lutarium and P. oopapillum on media amended with MBOA compared to the check at all temperatures. Similarly, more root rot caused by P. torulosum, and P. spinosum was observed when MBOA was present at 16 °C compared to the check with no MBOA.

These data suggest that corn seedling disease caused by Pythium species could be more severe when corn is planted following a cover crop of winter cereal rye due to the presence of allelochemicals that are released from the cover crop.

Other activities and accomplishments:

  • An Iowa Learning Farm Webinar